The use of flexible, electrically conductive contacts in switches for sensing edges is generally known. Such sensing edges generally include an elongate sheath enclosing a pair of compressible sheets sandwiching a third perforated compressible sheet. Attached to the opposing faces of the pair of compressible sheets are flexible, electrically conductive contacts Upon application of pressure to the sheath, the flexible, electrically conductive contacts are deflected through the perforations of the sandwiched compressible sheet into electrically conductive engagement with each other to thereby actuate suitable circuitry for controlling the door.
The problems associated with such sensing edges are inherent in the material used for the flexible, electrically conductive contacts. Typical contacts are constructed of thin sheets of metal (e.g., aluminum foil). These thin sheets are sometimes adhesively mounted on a nonconductive backing (e.g., plastic sheeting, plastic film, asbestos fabric). An inherent property, as well as problem, associated with the metallic sheets is memory. When the metal is folded or dented it tends to retain its new shape. Continued folding and denting of metallic contacts causes fatigue and eventually breakage. Since the sheets of metal which make up the contact are relatively thin, the strength of the sheet is limited.
Consequently, there exists a need in the sensing edge field for a flexible, electrically conductive contact with improved flexibility and durability and which minimizes the adverse effects of memory and fatigue.
The present invention is directed to a flexible, electrically conductive contact for use with a sensing edge to cause a closing door to open by actuating a device upon application of force to the sensing edge. The present invention overcomes many of the disadvantages inherent in the above-described flexible, electrically conductive contacts by providing a flexible, electrically conductive contact which is comprised of a plurality of interwoven generally flexible fibers wherein a portion of these fibers are constructed of an electrically conductive material. The flexible, electrically conductive contacts of the present invention are generally memoryless when folded or dented. Thus, the flexible, electrically conductive contact of the present invention are durable to thereby reduce repair and/or replacement costs. Accordingly, use of the present invention results in considerable savings in money as well as time for repair and reconstruction and/or replacement of sensing edges.